Window envelope



April 16, 1929. GEN-LE 1,709,126

WINDOW ENVELOPE Filed March 26, 1928 (50 1144? ilv k zzg Patented Apr. 16, 1929.

UNITED STATES PATENT OFFICE.

MARINO GENTILE, OF CHICAGO, ILLINOIS, ASSIGNOB OF ONE-HALF '10 SAMUEL W.

WEIS, OF CHICAGO, ILLINOIS.

Wm DOW ENVELOPE.

Application filed March 26, 1928. Serial No. 284,941.

This invention relates to mailing envelopes of the type commonly known as window envelopes, wherein the face of the envelope. is provided with a transparent portion or window which renders visible therethrough the name and address written or printed on the enclosure.

So far as I am aware, in envelopes in actual use the transparent section of the'front of the envelope has been provided in only two ways. In one way, oil is applied to the surface of the paper and allowed to dry, thus rendering the paper sufiiciently transparent to enable the name and address to be visible therethrough. According to the other method, an oblong slot is cut in the face of the envelope and a piece of so-called glazine pa per, which is transparent, is pasted to the under side of the front wall of the enevelope over said opening. Neither of these methods has proved entirely satisfactory, or yields the high degree of transparency required by postal regulations. Another process which has been proposed for producing transparent windows in paper, cardboard and the like consists in spreading a thin layer of gelatine or other colloidal matter, which will harden to form a solid transparent film, on a slab such as a sheet of glass, then depositing the so aperturedsheet on said layer and pressing, rubbing or brushing the sheet to cause it to adhere to the film, and, when the film is dry and hard, detaching it from the slab together with the sheet which it covers. I have found by actual experiment with this process that the product is a sheet, the windows of which are glazed by portions of a film which covers the whole sheet. The portions of the film which cover the openings do not fill the latter but lie almost wholly on one side, as in the glazine paper structure above referred to, while the remaining portions of the film constitute not only a useless waste of material, but unnecessarily increase the weight and lessen the flexibility of the sheet of paper.

The primary object of the present invention is to provide an improved window enve lopeof the general character above indicated which will yield a higher degree of transparency, will not involve any increase in the thickness of any portion of the front wall of the envelope nor decrease of its flexibility, will not present any loose edges to catch on or obstruct the p p of the enclosure into the envelope, may be simplyand economically manufactured, and will be strong and durable in use.

-An envelope embodying my present invention is illustrated in the accompanying drawing, in which Fig. 1 is a top plan view of the envelo e;

Fig. 2 is a longitudinal section throng the front wall on an enlarged scale, on the line 22 of Fig. 1;

Fig. 3 is a transverse section through the front wall on an enlarged scale, on the line 33' of Fig. 1;

Fig. 4 is a section similar to Fig. 2, showing a window of the same thickness as the wall in which it is formed.

In carrying out my invention, I first form an oblong opening or slot 10 in that portion 11 of the envelope blank which, when the envelope is folded and gummed into finished form, constitutes its front wall. According to one method the blank is then laid on a perfectly smooth flat hard surface, and a plastic semi-liquid or viscous transparent material such as gelatine, cellulose acetate, or nitrocellulose, is then sprayed or poured into the opening or slot 10 of the envelope blank, and is then by suitable rolls or other spreading means flattened and spread into adhesive edge contact with the edges of the opening, said plastic material being compressed to the same thickness as the paper of the front wall. The pressure is preferably maintained until the plastic material has become dry and hardened, during which drying it shrinks considerably in thickness, whereupon it forms a 9 filler or window 12 for the opening having a high degree of transparency, ossessing a thickness somewhat less than t e thickness of the wall 11, and securely adhered at its edges only to the edges of the opening. This filler is also flexible to approximately the same extent as the pa er itself, and lies wholly within the plane 0 the latter.

Accordin to another method of manufacture, after t e blank has been laid smoothly on a flat, hard surface, a die having an opening exactly registering with the opening 10 is laid on the blank, the plastic material is oured into the die opening, and the material is then compressed, spread and flattened by a plunger fitting the die opening. 7 When practising this method slightl more of the plastic material than will fill t e opening 10 may be poured in and, after being compressed and flattened, is left to dry. In drying out it shrinks, forming a window 12 (Fig. 4) of substantially the same thickness as the front wall of the enevelope, in adhesive edge conall well adapted for the purposes of my improved envelope, it is to be understood that any other plastic material possessing the properties' specified and transparent when hard and dry may be employed within the purview of the invention.

This application constitutes a continuation in art of, and a substitute for, an application 'or awindow envelope filed by me on the 24th day of September, 1926, Serial No. 137,437. I

I claim- 1. A'window envelope having an opening in its front wall, and a filler for said opening consisting of a strip of flexible transparent material in adhesive edge contact only with the edges of said opening.

2. A window envelope having an opening in its front wall, anda filler for said opening 'consisting of a strip of flexible transparent material in adhesive edge cont-act with the edges of said opening and of a thickness not greater than that of said wall and lying wholly within the plane of the latter.

3. A window envelope having an opening in its front wall, and a filler for said opening consisting of a strip of flexible transparent material in adhesive edge contact only with the edges of said opening and of a thickness less than the thickness of said wall. 

